When to call a Dr?

Tab
Hi, I posted in another forum but nobody wants to comment or anything so I thought I'd try here. 
I'm close to 5 weeks and I'm having diarrhea more than three times a day and I'm feeling faint/dizzy like I'm going to black out. I also have episodes of shortness of breath. 
Was wondering if I should call the doctor or if it's okay. I haven't been pregnant in over six years but my other two pregnancies were never like this in early pregnancy. Thank you.